Contained load transfer device for wood sheathing products and roof construction method therewith

ABSTRACT

The utilization of a specific load transfer device for the purpose of allowing for reliable connection and adhesion of composite wood boards during edifice manufacture therewith is provided. Such a device is configured for containment within slots cut into the peripheral edges of such wood boards and cut into a shape therein that is complementary to that of the device itself. In such a manner, the device, when introduced within the properly shaped slot, permits separation of adjacent wood boards that are sequentially applied to the frame of the target edifice, as well as, ultimately, sufficient load bearing strength for the overall construction (such as a roof) within which such connected wood boards are utilized. The separation of wood boards thus permits proper sealing therebetween (with tape, sealant, or other like material) as well as proper distance for shrinking or swelling (due to moisture/temperature variations) to be taken into account during the lifetime of the edification (thereby permitting expansion as needed). The ability to impart increased load bearing strength thus allows for an increase in construction materials (in number and in weight) to be carried and kept on such a structure during construction as well. The method of manufacture of an edifice utilizing such load transfer devices between wood boards is also encompassed within this invention.

FIELD OF THE INVENTION

The subject invention relates to the utilization of a specific loadtransfer device for the purpose of allowing for reliable connection andadhesion of composite wood boards during edifice manufacture therewith.Such a device is configured for containment within slots cut into theperipheral edges of such wood boards and cut into a shape therein thatis complementary to that of the device itself. In such a manner, thedevice, when introduced within the properly shaped slot, permitsseparation of adjacent wood boards that are sequentially applied to theframe of the target edifice, as well as, ultimately, sufficient loadbearing strength for the overall construction (such as a roof) withinwhich such connected wood boards are utilized. The separation of woodboards thus permits proper sealing therebetween (with tape, sealant, orother like material) as well as proper distance for shrinking orswelling (due to moisture variations) to be taken into account duringthe lifetime of the edification (thereby permitting expansion asneeded). The ability to impart increased load bearing strength thusallows for an increase in construction materials (in number and inweight) to be carried and kept on such a structure during constructionas well. The method of manufacture of an edifice utilizing such loadtransfer devices between wood boards is also encompassed within thisinvention.

BACKGROUND OF THE INVENTION

Composite wood boards, such as plywood boards or oriented strand boards,are well-known in the construction industry. In fact, such boards areused in the manufacture of inclined roofs. To facilitate making theroofs, board manufacturers sell rectangular boards which are about fourfeet wide, eight feet long and about ⅜ to ¾ of an inch thick. Suchboards are generally not attached to a roofing frame with each boardabutting another. Such spacing is required to compensate for expansionpossibilities due to changes in moisture content during the lifetime ofthe roof itself. As such, there is needed a manner of providing sealingbetween the spaces of such roof component boards. This is typicallyaccomplished with tape, or any other like material. The tape is appliedto ends of adjacent boards and across such spaces.

Also necessary of such roof structures and thus the component boardsthereof is the capacity to withstand excessive weights due to the loadsof workers present on the roof during construction as well as thematerials applied during such a construction project (and, furthermore,the combined weight of a worker carrying such materials on said roof).Additionally, there is a need to ensure that such boards that constitutethe roof structure must stay in place for sufficient time to bepermanently attached to the underlying roofing frame.

In order to permit such an outcome, there have been utilized certaindevices in the form of clips that contact the outside edges of adjacentboards (on both the top and bottom thereof). Such clips, known in theindustry as H-clips, exhibit disadvantages, however, that render themhighly undesirable for such a purpose. For instance, such H-clips makeit difficult to apply adhesive tape (for, among other purposes, sealingseams to prevent water penetration therein and air leaks) along thespaces between boards conjoined by such clips, particularly since suchclips are applied to the exterior of such boards. The adhesive tapeapplied to such boards must thus be in contact with such clips as wellas such boards, thereby exhibiting a certain reduction in potentialadherence thereto and compromising the effectiveness of such tape (orlike adhesive material). Also, it has been problematic to apply certainload forces to roof structures including such H-clips, particularlyduring manufacturing steps thereof, as such clips exhibit a propensityfor disengaging upon application of excessive weight on certain portionsof component boards. As such, there exists a need and desire to removesuch H-clips from utilization for such a purpose while still providing aviable manner of permitting effective connection between adjacent boardsduring roof construction, and while simultaneously allowing forapplication of materials via adhesion thereof to adjacent boards withoutlosing the effectiveness of such adhesive materials. To date, the woodboard roofing component industry has not been accorded such animprovement.

ADVANTAGES AND BRIEF DESCRIPTION OF THE INVENTION

It is an advantage of the present invention to provide a simple mannerof reliably connecting building roof component wood boards togetherduring roof construction therewith. Another advantage of such a deviceand method is the ability of a user to easily install such deviceswithin target wood boards and further connect an adjacent wood boardthereto through the utilization of at least one such device in order tokeep such wood boards in place for a sufficient period of time prior toattachment to a roof frame.

The invention herein may be summarized as a structure for an edificeselected from the group consisting of a roof and a wall, wherein saidstructure is comprised of at least a first wood board and a second woodboard, each of said first and second wood boards having a top portionand a bottom portion, and each having four peripheral edges, wherein atleast one peripheral edge of each wood board includes at least onecavity therein for the insertion of at least one connection device;wherein said connection device is made of a durable material and havinga first end and a second end and wherein each of said first and secondend is configured to be inserted within said at least one cavity of eachwood board; wherein when said first and second wood boards are contactedsimultaneously with said device, said peripheral edges into which saiddevice is inserted are parallel to each other, but are not in contactwith one another, and wherein said device does not contact the top orbottom portion of said first and second wood boards. Furthermore, theroof or wall structure as defined above may include limitations such as:wherein said first end and said second end are shaped exactly the sameand of the same dimensions, wherein said device is configured in such amanner that either of said first or second end may be placed within saidat least one cavity within said peripheral edge of said first woodboard, said cavity exhibiting a shape and dimension that iscomplementary to said first or second end of said device, and whereinwhen present within said cavity of said first wood board, said secondwood board may then be contacted with said second end of said device inrelation to the same type of cavity as defined for said first wood boardwithin said peripheral edge of said second wood board. A method ofmanufacturing a roof in accordance with such a scheme and utilizing atleast two such wood boards for such a purpose is encompassed within thisinvention as well.

Such a device should therefore preferably be symmetrical in shape andmeasurements in order to exhibit the necessary ability to be insertedwithin cavities of any wood board used therewith. The size of such adevice may be of any width, up to the length of the peripheral edge ofthe target wood board(s) less an inch and a half (i.e., about 3.8centimeters), generally. As the length of typical spacing between roofjoists for roof construction wood boards are about 24 inches on center(i.e., about 61 centimeters), such a device may thus be as wide as 22.5inches (roughly about 57 centimeters). At its smallest, such a devicewould be about 1 inch (2.54 centimeters) wide. Preferably, though notnecessarily, a multiple amount of such devices would be utilized toconnect adjacent boards together during the construction of a roof orwall, mainly because of the facilitation of maneuverability a user wouldhave with smaller devices in hand during roof construction, rather thanlarge materials for such a purpose.

As such, the device may be incorporated within a roll containing arelease liner with an adhesive attaching such multiples of devices tothereto from which they may be peeled and applied within the cavities ofwood boards, potentially with the adhesive transferred therewith topermit reliable attachment of such devices to target wood boards. Inthis manner, a user would have a relatively convenient and safe mannerof not only transporting such multiple devices, but also applying anadhesive-including device to a target wood board.

The utilization of an adhesive is also preferable if the device(s) aretransported by a user by different means. As such, an adhesive may beapplied by the user by hand prior to utilization, or such devices mayhave covering strips over an already-applied adhesive area thereon, fromwhich the strip may be removed by the user prior to utilization andinsertion within a wood board cavity. Any other manner of adhesiveapplication may also be followed for such a purpose.

The device itself may be constructed of any durable material, and of anyshape and dimension, as long as the overall appearance is, as notedabove, symmetrical. Thus, plastics (including high density plastics likepolyurethane, polyethylene, polypropylene, polyethylene terephthalate,polyacrylate, polyacetyl, and the like), metals (including iron, steel,aluminum, and the like), and any type of hardwood (oak, cedar, and thelike), may be utilized to such an end. Combinations of such materials(such as mixtures of different plastics, a plastic coated metal or wood,and the like), may also be utilized.

A device having an increased surface area through texturing, roughening,and the like, over the faces or edges or both, thereof, may also beemployed, particularly if an adhesive is utilized in conjunctiontherewith. Such an increase in surface area thus may contribute anincrease in adhesive force during utilization and possibly strengthenthe joint (like a truss plate, for example).

As noted above, it was vitally important to provide a manner ofconnecting adjacent wood boards together wherein such boards do notcontact one another during installation. This distance may be from about1/16 inch to about ¼ inch, generally, and thus would require the depthof the cavities present within the wood boards to equal less than halfthe overall length of a single device. Building codes of variousjurisdictions have varying requirements in terms of such spacings, but apopular distance is ⅛ inch for such a gap between adjoining edges (toallow for expansion and contraction of the panels due to moisture and/ortemperature variations). This may be accomplished by providing an LTD ofsufficient length that upon insertion within the cavities of adjoiningboards, the gap is substantially uniform and cannot be breached.Alternatively, the LTD may be produced with a post in the center thereofto provide such spacing upon utilization.

As the cavity should preferably be complementary in shape and dimensionto the device, any such shape or dimension may be employed for thedevice and wood board cavity as long as they meet such requirements.Thus, if the device is an oval-shaped disk, the cavity will likewiseexhibit a complementary oval indentation of the same measurements. Ifthe device is a rectangular disk, again, the cavity (slot) will beformed to accept such a shape and measurements. In one particularlypreferred embodiment, the device may include a pin at the very middlethereof to aid in distancing the adjacent wood boards from one another.Furthermore, the cavity (slot) may also include a flared portion (orpost portion, as noted above) to facilitate insertion of such a flatdevice therein and further facilitate the insertion of the other end ofsuch a device within the cavity of a second wood board during roofconstruction.

Additionally, and as noted above, the need to permit reliableapplication of tape thereto necessitated development of a device thatwould not have any contact with both the top and bottom of a wood boardduring utilization. Thus, the overall method would permit insertion ofsuch a device, or plurality of devices, within at least two wood boardssimultaneously without any contact between the two wood boards, but withthem residing in parallel relation to one another, and without anycontact between the device, or plurality of devices, and the top andbottom portion of either wood board connected thereto.

Such a method provides more than just a manner of connecting roof orwall component wood boards prior to attachment to a roofing or wallframe, as well as more than just a manner of permitting tape to bereliably adhered to the subject wood boards in the areas in which theyare not in contact with one another. In addition to those highlydesirable results, it was surprisingly realized that such a methodimparts a heretofore unforeseen ability to withstand larger than usualload forces associated with the weight of a construction worker and thematerials such a person would normally be required to transport over aroof during construction thereof. Such load bearing results arediscussed in greater detail below.

The wood boards that may be utilized for such roof construction may beof any type, including oriented strand board, plywood, and the like.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned and other objects of invention will become apparentby reference to the following description in conjunction with theaccompanying drawings, in which:

FIG. 1 is a cross-sectional view of an oval-shaped disk inserted withinthe cavities of peripheral edges of adjacent wood boards.

FIG. 2 is a cross-sectional view of an oval-shaped disk exhibiting anincreased surface area.

FIG. 3 is a cross-sectional view of a rectangular-shaped disk exhibitingan increased surface area.

FIG. 4 is a cross-sectional view of a rectangular-shaped disk having apin present at its midpoint and inserted within the cavities of two woodboards, each exhibiting flares to facilitate insertion thereof duringuse.

DESCRIPTION OF A PREFERRED EMBODIMENT

FIG. 1 shows a cross-sectional perspective of a disk 10 inserted withinthe cavities 12, 14 of peripheral edges 13, 15 of two adjacent woodboards 16, 18. As can be seen, the disk 10 is flush with the internalportions of said cavities 12, 14 to the degree that a distance betweenboth boards 16, 18 is evident. A tape (not illustrated) may then beapplied in contact with the top portions 20, 22 of both wood boards 16,18. When multiple disks are utilized, the distance between the woodboards 16, 18, will be roughly uniform along the peripheral edges 13,15.

The disks of FIGS. 2 and 3 merely show that such devices, either oval inshape 24, or rectangular in shape 26, may be modified or producedoriginally in such a manner as to impart an increase in surface areathereto to aid in adhering such devices to the cavities in which theyare inserted within wood boards (not illustrated).

FIG. 4 depicts a cross-sectional perspective of a different potentialembodiment wherein the disk 28 includes a pin at its midpoint 30 to aidin keeping the distance between the boards 32, 34 uniform and inparallel relation thereto. If such boards 32, 34 are not kept parallelto one another, the skewed result could deleteriously affect the spacingof other portions of the target roof. Also, the flared portions 36, 38of the wood boards 32, 34 allow for insertion of the disk 28 havingportions near the midpoint that complement the shape of such flares 40,42, thereby facilitating insertion of the disk 28 within the cavities44, 46 within the peripheral edges 48, 50 of the wood boards 32, 34 aswell as permitting a firm and snug fit of the disk 28 therein duringuse.

To insure that the load transfer device of this invention is capable ofproviding the necessary load capacity, concentrated load testing wasdone comparing the load transfer device of this invention to currentload transfer devices (“H”-clips) used today in the constructionindustry. Building codes and regulations generally require thatsheathing with a span rating of Roof-24 must not exceed 0.5″ ofdeflection under a 200 pound load. Previous testing conducted usingH-clips revealed that the H-clip would fall from the specimen prior tothe completion of the test. Sampling of the inventive loadbearing/transfer device (biscuit) indicated that it would break theshoulder (the portion of the board that surrounds the cavity into whichthe biscuit, clip, or other device, is inserted during utilizationthereof) either above or below the area where it was placed; however,the specimen would still pass the requirement set forth by theaforementioned building codes and regulations (known in the industry asPS-2). The inventive load transfer device in a manner thus maintains itsintegrity upon use in such a manner (i.e., the biscuit would remain inplace when a concentrated load was applied at its location).

The cavity in the target wood board may be configured as well in anyshape, particularly at the entry point, in order to facilitate ingressof the LTD itself. Thus, the edge of the point of entry may be curved,tapered, or any like effect, to permit such ease in application. Thiswill be important in most instances to facilitate such application whilea user has a number of tools and other implements in his/her hands.

It is accepted that the highest concentrated loads on roof sheathing areanticipated under foot traffic during construction. For example, a200-lb man carrying an 80-lb bundle of shingles down a roof slope canexert a load up to 68% greater than his combined total weight (Harper,F. C., et al. 1961. The Forces Applied to the Floor by the Foot inWalking. Research Paper 32. National Building Studies, London, England).Since the walking loads are applied for less than one second, the totalload can be reduced by a load-duration factor of 1/1.22 for short-termtests, as follows:$\frac{\left( {200 + 80} \right)(1.68)}{1.22} = {386\quad{lbs}}$

The effective load is even less (up to 280 lbs) if the man stands in onelocation for a short period of time, and in addition, the load isdistributed over a larger area by both feet.

In the light of the foregoing, a minimum load of 400 lb would give asmall margin of safety, which is justified considering the uncertaintiesof construction. Therefore, it is important that any load transferdevice remain intact up to a 400 lb concentrated load.

Different inventive load transfer/bearing devices (biscuits) made fromdifferent materials and of various dimensions were produced and analyzedin order to determine the effectiveness of such devices to withstandsuch loads upon use. The materials in accordance with the design shownin FIG. 1, above, were as follows: Thickness ⅛″ 1/16″ Material Length ofLTD Wood 1.75″ Steel 2.2″-3.5″ Acetyl 2″-3.5″-4.5″ High densitypolyethylene 2″-3.5″-4.5″ Aluminum 2″-3.5″-4.5″

The modulus of elasticity of some of these materials were important aswell in determining their effectiveness. It was realized that thegreater the elasticity, the better the disk, biscuit, etc., madetherefrom was able to withstand load bearing weights to a greaterdegree. It is believed, without intending to be limited to any specificscientific theory, that such greater load bearing capability is providedin relation to the flexibility of the device and thus the capacity ofsuch a material to simultaneously bear weight when applied directly tothe area affected, as well as the area adjacent thereto. A material withvery high stiffness appeared to force the device to break the shoulderportion of the board before the device itself was injured to anyappreciable extent. A material with a much lower stiffness allowed moredeflection of the device and joint under concentrated loads. Thus,although any of these materials will suffice within the invention aspresented, preferably the device is a material exhibiting a MOE of10,000,000 psi or below, more preferably lower than 1,000,000 psi, andmost preferably from 100,000 to about 500,000 psi. High densitypolyethylene exhibits a MOE of about 200,000 psi and polyacetal fromabout 305,000 to about 380,000 psi. Aluminum is as high as 10,000,000.This list is not exhaustive of the potential materials available forthis invention, but illustrative thereof.

The manner of measuring load bearing was undertaken as follows:

First, a comparison of how the below surface LTD's vs. H-clips performedunder a concentrated load was conducted. To meet PS-2 requirements, thepanel/LTD must:

a) Not to exceed 0.5″ deflection under a 200 pound concentrated load;and

b) Exceed 400 pound ultimate load (such as under foot traffic, asdescribed above).

Another functional product requirement that was deemed important, evenif PS-2 requirements were met, is the ability of the entire panel(s)plus LTD not to exhibit any breaking of the shoulders at the placementarea of the below surface LTD prior to reaching a 400 lb concentratedload.

The analysis performed to determine this desired level of effectivenesswas an analysis of variance calculation. In essence, in order to avoidthe possibility of having a person become injured during actual testingof a constructed roof or a roof being constructed, the subjectstructures were analyzed in a lab environment for deflection and loadbearing capability. A TECO QL-2 Panel Performance Tester was utilizedfor such analysis. Such an instrument is a fully automated,computer-controlled machine designed to perform testing that isconsistent with PS 2-92 concentrated static, impact load and deflectiontest requirements. The instrument is equipped with a “floating bed” thatfacilitates impact testing, as well as instrumentation to test forconcentrated load and deflection, ultimate (failure) load, impact load,and edge-supported panels. The test panels were about 7/16 inch inthickness (the machine can test for thicknesses between ¼ and 1⅛ inches,and the length of subject panels (boards) can be from 16 to 48 inches.In the test utilizing two boards connected via the inventive device, 48inch boards were used. Generally, simulated joists (three in all) wereincluded within the instrument to permit testing comparable to loadbearing of roofing sheathing during installation of boards havingdimensions of 48 inches (121.92 cm) by 96 inches (243.84 cm). A boardwas connected thereto the simulated joists and 4 inventive devices werethen inserted within the cavities provided therein the periphery of theboard (the devices were about 8 inches in length and insertedwidthwise). A second board of the same dimensions and havingcomplementary cavities therein for connection to the already inserteddevices was then supplied. That board was then connected via the deviceswithout contacting directly the first board. A floating panel bed wasthen moved into place beneath the two device-connected boards andpressures were then supplied to specific areas of the boards to measureload bearing and deflection thereof. A pneumatic pressure applicator wasutilized and was applied hydraulically at two locations on the subjectboards (in accordance with the PS 2-92 test requirements) and read by a2,000 pound capacity load cell. A high-resolution digital encoder wasutilized to record the deflection after the pressure (weight) wasapplied as well.

Thus, upon application of the weight (pressures) tested, themeasurements were taken as calculation by an analysis of variance(ANOVA) method. Such a method is similar to regression in that it isused to investigate and model the relationship between a responsevariable and one or more independent variables. However, analysis ofvariance differs from regression in two ways: the independent variablesare qualitative (categorical), and no assumption is made about thenature of the relationship (that is, the model does not includecoefficients for variables). In effect, analysis of variance extends thetwo-sample t-test for testing the equality of two population means to amore general null hypothesis of comparing the equality of more than twomeans, versus them not all being equal. A two-way analysis of variancetests the equality of populations means when classification oftreatments is by two variables or factors.

It was assumed that the population means in each test was the same andcomputed a p-value for the sample means in order to determine thedifference in the samples means. This method thus considers thelikelihood that two sample means would be a certain distance apart ifthey come from two processes with the same mean. If the p-value issmall, it was concluded that the population means were different (i.e.,less than 0.05).

The abbreviations below are as follows:

DF=Degrees of Freedom. The extent to which the distribution was morespread out. As this measurement gets larger, the distribution dispersiongets smaller.

SS=Sum of Squares. This represents total variation of measurements.

MS=the MS error is the pooled standard deviation squared.

F=F test. Such a test answers the question if the two populationvariances are different.

This test determines if the two populations exhibit similar ordissimilar factors and thus uses samples variances between thepopulations tested. This does not, however, actually test the degree ofdifference in sample variances, only if they exist. A value of greaterthan 4 for an F-value is significant whereas as close to 1 as possiblemeans the group means of measurements are very similar between the twopopulations.

Thus, the analyses were followed as noted below: TABLE 1 ANOVA showingdeflection under a 200 lb concentrated load using below surface LTD'sand H-clips Source DF SS MS F P Material  5 0.15101 0.03020 4.68 0.002Error 35 0.22602 0.00646 Total 40 0.37703 S = 0.08036 R-Sq = 40.05%R-Sq(adj) = 31.49% Individual 95% CIs For Mean Based on Pooled StDevLevel N Mean StDev −−−−−−−−+−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+− Acetyl  60.25117 0.02522  (−−−−−−−*−−−−−−−−) Aluminum  6 0.24100 0.03013(−−−−−−−*−−−−−−−) H-Clips 10 0.38790 0.09954                    (−−−−−*−−−−−−) HDPE  6 0.28133 0.08078     (−−−−−−−*−−−−−−−) Steel  9 0.36578 0.10176                 (−−−−−−*−−−−−−) Wood  4 0.37500 0.06746               (−−−−−−−−−*−−−−−−−−−)−−−−−−−−+−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+−      0.240    0.320    0.400    0.480 Pooled StDev = 0.08036

The initial testing indicated that Acetyl and Aluminum below surfaceLTD's were significantly better than H-clips in relation to deflectionunder a 200 lb concentrated load. The steel, wood and HDPE were notsignificantly different than H-clips.

Further testing was then followed to determine if ultimate concentratedloads were different in terms of capability of load bearing by thesubject load transfer device(s). TABLE 2 ANOVA showing ultimateconcentrated load of below surface LTD's and H-clips Source DF SS MS F PMaterial  5  37397 7479 0.82 0.546 Error 35 320691 9163 Total 40 358088S = 95.72 R-Sq = 10.44% R-Sq(adj) = 0.00% Individual 95% CIs For MeanBased on Pooled StDev Level N Mean StDev −+−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+−−−−−−−− Acetyl  6 663.50 145.02               (−−−−−−−−−−−*−−−−−−−−−−) Aluminum  6 562.67  52.63  (−−−−−−−−−−*−−−−−−−−−−−) H−Clips 10 614.10  81.37           (−−−−−−−−*−−−−−−−−) HDPE  6 618.00  70.59         (−−−−−−−−−−*−−−−−−−−−−−) Steel  9 584.67  90.97      (−−−−−−−−−*−−−−−−−−) Wood  4 621.50 130.36       (−−−−−−−−−−−−−*−−−−−−−−−−−−−) −+−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+−−−−−−−− 490      560      630      700Pooled StDev = 95.72

Testing also indicated that all below surface LTD's were notsignificantly different than H-clips.

Thickness variations in the inventive devices were then tested. TABLE 3ANOVA showing deflection under a 200 lb concentrated load using twodiferent thicknesses of below surface LTD's Source DF SS MS F PThickness  1 0.09264 0.09264 18.87 0.000 Error 29 0.14236 0.00491 Total30 0.23500 S = 0.07006 R-Sq = 39.42% R-Sq(adj) = 37.33% Individual 95%CIs For Mean Based on Pooled StDev Level N Mean StDev−−−−−+−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+−−−− 0.0625 18 0.25783 0.05181(−−−−−−+−−−−−) 0.1250 13 0.36862 0.08978                     (−−−−−−−*−−−−−−−)−−−−−+−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+−−−−   0.250    0.300    0.350   0.400 Pooled StDev = 0.07006

Testing conducted on the two thicknesses of below surface LTD'sindicated that the 0.0625 inch thick LTD's performed significantlybetter in relation to deflection under a 200 lb concentrated load thanthe 0.125 inch thick LTD's (See FIG. 3, for instance).

Ultimate concentrated load was then tested for the same devices ascomparisons. TABLE 4 ANOVA showing ultimate concentrated load of twodifferent thicknesses of below surface LTD's Source DF SS MS F PThickness  1   2646  2646 0.26 0.614 Error 29 295462 10188 Total 30298107 S = 100.9 R-Sq = 0.89% R-Sq(adj) = 0.00% Individual 95% CIs ForMean Based on Pooled StDev Level N Mean StDev−−−−−−+−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+−−− 0.0625 18 614.7 101.3        (−−−−−−−−−−−−−*−−−−−−−−−−−−−) 0.1250 13 596.0 100.4(−−−−−−−−−−−−−−−*−−−−−−−−−−−−−−−)−−−−−−+−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+−−−    560      595      630      665 Pooled StDev = 100.9

Testing indicated that there are no significant differences between thetwo thicknesses investigated in relation to ultimate concentrated load(See Table 4).

Breaking load was then analyzed for these same devices. TABLE 5 ANOVAshowing breaking load under a concentrated load of two diferentthicknesses of below surface LTD's Source DF SS MS F P Thickness  1208121 208121 28.40 0.000 Error 29 212516   7328 Total 30 420637 S =85.60 R-Sq = 49.48% R-Sq(adj) = 47.74% Individual 95% CIs For Mean Basedon Pooled StDev Level N Mean StDev −+−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+−−−−−−−− 0.0625 18 415.28  73.09                       (−−−−−+−−−−−) 0.1250 13 249.23 100.70 (−−−−−−*−−−−−−)  −+−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+−−−−−−−−210      280      350      420 Pooled StDev = 85.60

Testing has indicated that the 0.0625-inch below surface LTD issignificantly better in relation to breaking load than the 0.125-inchbelow surface LTD.

Given that concentrated load testing has indicated that below surfaceLTDs can perform as well as H-clips, continued testing on geometries wasconducted to optimize the below surface LTD. Given that it has beendetermined that the 0.0625-inch below surface LTD performs significantlybetter in relation to deflection under a 200 lb concentrated load andbreaking load than the 0.125-inch below surface LTD's, the 0.125-inchLTD's were dropped from further evaluation.

Further testing was conducted on the 0.0625-inch thick acetyl, aluminumand HDPE in three sizes: 2.25″, 3.5″ and 4.5″. TABLE 6 ANOVA showing thedeflection at a 200 lb concentrated load in relation to the three sizesof below surface LTD's tested Source DF SS MS F P Biscuit Size  20.01299 0.00649 2.98 0.081 Error 15 0.03264 0.00218 Total 17 0.04563 S =0.04665 R-Sq = 28.46% R-Sq(adj) = 18.92% Individual 95% CIs For MeanBased on Pooled StDev Level N Mean StDev−−−+−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+−−−−−− 2.25 6 0.25083 0.01951      (−−−−−−−−−*−−−−−−−−−) 3.50 6 0.22900 0.03472 (−−−−−−−−−*−−−−−−−−−)4.50 6 0.29367 0.07030                 (−−−−−−−−−*−−−−−−−−−)−−−+−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+−−−−−− 0.200    0.240    0.280    0.320 Pooled StDev = 0.04665

TABLE 7 ANOVA showing the ultimate concentrated load between threedifferent sizes of below surface LTD's tested Source DF SS MS F PBiscuit Size  2  16736  8368 0.80 0.469 Error 15 157778 10519 Total 17174514 S = 102.6 R-Sq = 9.59% R-Sq(adj) = 0.00% Individual 95% CIs ForMean Based on Pooled StDev Level N Mean StDev−+−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+−−−−−−−− 2.25 6 571.7  58.2 (−−−−−−−−−−−−*−−−−−−−−−−−) 3.50 6 638.3  75.2          (−−−−−−−−−−−−*−−−−−−−−−−−−) 4.50 6 634.2 150.0          (−−−−−−−−−−−−*−−−−−−−−−−−)−+−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+−−−−−−−− 490      560     630       700Pooled StDev = 102.6

TABLE 8 ANOVA showing breaking load during concentrated load testingusing diferent size below surface LTDs Source DF SS MS F P Biscuit Size 2  9678 4839 0.89 0.430 Error 15 81146 5410 Total 17 90824 S = 73.55R-Sq = 10.66% R-Sq(adj) = 0.00% Individual 95% CIs For Mean Based onPooled StDev Level N Mean StDev −−−−−−+−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+−−−2.25 6 385.83 82.12 (−−−−−−−−−−−−*−−−−−−−−−−−−) 3.50 6 417.50 92.13       (−−−−−−−−−−−−*−−−−−−−−−−−) 4.50 6 442.50 31.58            (−−−−−−−−−−−−*−−−−−−−−−−−)−−−−−−+−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+−−−   350       400       450      500 Pooled StDev = 73.55

Testing has thus indicated that there are no significant differences inrelation to deflection under a 200 lb concentrated load, ultimateconcentrated load and breaking load between the different sizematerials.

Although there is no significant difference between the different sizematerials, there seems to be a pattern that indicates that the bigger(longer) below surface LTDs are better suited to meet the requirement ofa minimum 400 lb. breaking load. Furthermore, it appeared from theanalysis results that the acetyl material exhibited less propensity tobreak the shoulders above or below the LTD during testing, even atultimate load, than the other materials. Thus, such a material ispreferred over the others, though not required.

While the invention will be described and disclosed in connection withcertain preferred embodiments and practices, it is in no way intended tolimit the invention to those specific embodiments, rather it is intendedto cover structural equivalents and all alternative embodiments andmodifications as may be defined by the scope of the appended claims andequivalence thereto.

1. A structure for an edifice selected from the group consisting of aroof and a wall, wherein said structure is comprised of at least a firstwood board and a second wood board connected simultaneously to at leastone connection device; wherein each of said first and second wood boardshas a top portion and a bottom portion, and each has four peripheraledges, wherein at least one peripheral edge of each wood board includesat least one cavity therein for the insertion of at least one connectiondevice; wherein said connection device is made of a durable material andhaving a first end and a second end; wherein said end of said device isinserted within said at least one cavity of said first board and saidsecond end of said connection device is inserted within said at leastone cavity of said second board; wherein said peripheral edges of saidfirst and second wood board into which said connection device isinserted are parallel to each other, but are not in contact with oneanother; and wherein said connection device does not contact the top orbottom portion of said first and second wood boards.
 2. The structure ofclaim 1 wherein said first end and said second end of said connectiondevice are shaped exactly the same and exhibit the same dimensions. 3.The structure of claim 2 wherein said at least one cavity within saidfirst board and wherein said at least one cavity within said secondboard are both of a shape and dimensions complementary to that of eitherof said first end or said second end of said connection device.
 4. Thestructure of claim 1 wherein a plurality of cavities are present withinsaid first and second boards and a plurality of connection devices areinserted within at least two of said plurality of cavities.
 5. Thestructure of claim 4 wherein each of said plurality of connectiondevices is substantially identical and has a first end and said secondend substantially shaped the same and exhibiting substantially the samedimensions.
 6. The structure of claim 5 wherein said plurality ofcavities within said first and second boards are substantially identicaland exhibit substantially the same shape and dimensions, and whereinsaid cavity shape and dimensions are complementary to that of either ofsaid first end or said second end of said plurality of substantiallyidentical connection devices.
 7. The structure of claim 1 wherein saidat least one connection device exhibits a roughened appearance on itssurface.
 8. The structure of claim 1 wherein said at least oneconnection device exhibits an adhesive layer on its surface.
 9. Thestructure of claim 1 wherein said at least one connection deviceincludes a pin structure to separate said first and second boards asubstantially uniform distance.
 10. The structure of claim 1 whereinsaid cavities of said first and second wood boards are flared tofacilitate insertion thereof of said at least one connection device. 11.The structure of claim 3 wherein said at least one connection deviceexhibits a roughened appearance on its surface.
 12. The structure ofclaim 3 wherein said at least one connection device exhibits an adhesivelayer on its surface.
 13. The structure of claim 3 wherein said at leastone connection device includes a pin structure to separate said firstand second boards a substantially uniform distance.
 14. The structure ofclaim 3 wherein said cavities of said first and second wood boards areflared to facilitate insertion thereof of said at least one connectiondevice.
 15. The structure of claim 4 wherein each of said plurality ofsubstantially identical connection devices exhibits a roughenedappearance on its surface.
 16. The structure of claim 4 wherein each ofsaid plurality of substantially identical connection devices exhibits anadhesive layer on its surface.
 17. The structure of claim 4 wherein eachof said substantially identical connection devices includes a pinstructure to separate said first and second boards a substantiallyuniform distance.
 18. The structure of claim 4 wherein each of saidsubstantially identical plurality of cavities within said first andsecond wood boards are flared to facilitate insertion thereof of saidplurality of substantially identical connection devices.
 19. Thestructure of claim 6 wherein each of said plurality of substantiallyidentical connection devices exhibits a roughened appearance on itssurface.
 20. The structure of claim 6 wherein each of said plurality ofsubstantially identical connection devices exhibits an adhesive layer onits surface.
 21. The structure of claim 6 wherein each of saidsubstantially identical connection devices includes a pin structure toseparate said first and second boards a substantially uniform distance.22. The structure of claim 6 wherein each of said substantiallyidentical plurality of cavities within said first and second wood boardsare flared to facilitate insertion thereof of said plurality ofsubstantially identical connection devices.